1. Field of the Invention
The invention relates to a semiconductor device, and particularly to a semiconductor device having a power device of a voltage drive type.
2. Description of the Background Art
In general, a semiconductor device having a semiconductor element is connected to an external system side via a main electrode and a signal terminal. The main electrode passes a main current to the semiconductor element in an on operation or an off operation. A drive signal (gate drive signal) is transmitted from the system side to the signal terminal for causing the semiconductor device to perform the on operation or the off operation. This drive signal is transmitted as a voltage from the system side such as an inverter.
As an example of the above semiconductor device, Japanese Patent Laying-Open No. 2004-087871 (Patent Document 1) has disclosed a temperature sensing device of a semiconductor switch element. This patent document 1 has disclosed a temperature sensor, a non-contact temperature transmitting device and a power supply circuit. The temperature sensor senses a temperature in a desired position of the semiconductor switch element. The non-contact temperature transmitting device transmits, in a non-contact manner, a sensed temperature value obtained by the temperature sensor that is attached to the semiconductor switch element to a position remote from the semiconductor switch element. The power supply circuit uses, as a power supply, a gate signal provided to the semiconductor switch element, and supplies an operation power to the temperature sensor and the non-contact temperature transmitting device.
Japanese Patent Laying-Open No. 2006-324525 (Patent Document 2) has disclosed a method of signal transmissions between chips (semiconductor elements). The patent document 2 has disclosed the signal transmission method in which a second inductor element receives a first signal issued from a first inductor element and outputs it as a second signal, and particularly has disclosed the method in which the second inductor element receives the first signal and outputs the received signal by electromagnetic induction. The chip has a gate electrode that is driven by a pulse (drive signal) generated by a pulse generating circuit.
Japanese Patent Laying-Open No. 2000-020665 (Patent Document 3) has disclosed a semiconductor device provided with an LSI chip and an antenna. According to the disclosure of the patent document 3, the antenna receiving an electromagnetic wave generates an electric power by electromagnetic induction, and supplies it to an LSI chip (semiconductor element) so that the LSI chip operates,
According to the patent documents 1 to 3, a drive signal terminal for transmitting the drive signal to the semiconductor element inside the device must be electrically connected to a signal issuing unit on the system side. The semiconductor devices have been used in extremely wide ranges, and it is important to ensure reliability of electric connection between the system side and the semiconductor device.
The foregoing patent documents have not disclosed the electric connection between the drive signal issuing unit on the system side and the drive signal terminal of the semiconductor device described above. For example, the following three techniques may be employed for the electric connection between the drive signal issuing unit and the drive signal terminal. In a first technique, the drive signal terminal is joined to the drive signal issuing unit by solder. In a second technique, a connector is used, and the signal terminal is electrically connected to the drive signal issuing unit by a frictional force of the connector. In a third technique, a spring is used, and the drive signal terminal is electrically connected to the drive signal issuing unit by a pressing force applied to a surface.
However, the electric connection by the solder in the first technique suffers from the following problem. In recent years, lead-free solder has been used in view of environment. The lead-free solder generally has a high melting point. Therefore, a heat that is applied for soldering the drive signal issuing unit to the drive signal terminal is liable to damage at least one of the drive signal issuing unit and the signal terminal. This lowers the reliability of the semiconductor device.
When a stress is applied to a joined portion of the solder, e.g., due to vibrations, a crack or the like may occur. This lowers the reliability of the electric connection between the signal issuing unit and the drive signal terminal. When the reliability of the electric connection between the signal issuing unit and the drive signal terminal lowers, the drive signal cannot be transmitted reliably to the semiconductor device.
The electric connections by the connector or the spring in the foregoing second and third techniques suffer from the following problem. When a stress, e.g., due to vibrations is applied, the state of contact between the drive signal terminal and the drive signal issuing unit changes. Thereby, the drive signal issuing unit may be electrically disconnected from the drive signal terminal, which lowers the reliability of electric connection between the drive signal issuing unit and the drive signal terminal. Consequently, the drive signal cannot be transmitted reliably to the semiconductor element.